Mercury switch



June 1, 1943. l C, w TRAUTMAN 2,320,682

MERCURY SWITCH Filed Dec. 6, 1940 Patented June 1, 1943 MERCURY SWITCH Charles W. Trautman, Elkhart, Ind., assignor, by

mesne assignments, to Herbert E. Bucklen,

Elkhart, Ind.

Application December 6, 1940, Serial No. 368,779

3 Claims. (01. 20G-152)' This invention relates to mercury switches, and more particularly is concerned with mercury switches of the type used for illuminating glove compartments, trunk openings, doors and the like in vehicles in which the switch is tilted from one position to the other to open and close a circuit therethrough.

One of the primary objects of the present invention is to make a switch of this class which is very inexpensive, can be made of simple parts, and can be readily assembled.

The switch is designed to take a relatively low current, usually being operated on a storage battery or like circuit, and consequently the switch does not need any great current capacity but must be reliable in operation and simple in construction.

It is also desirable that the switch be of very simple compact form so that it can be contained within a simple bracket along with a lamp, preferably one terminal of the switch being directly connected to the lamp base.

One of the particular features of distinct ad# vantage in the present invention is the utilization of the construction in which the shell is of smooth bore, presenting no interference to the movement of the mercury during the tilting of the switch.

Since the switch is not used on heavy currents, I have found it unnecessary to provide a structure which is of the evacuated type, such as is commonly employed in connection with mercury switches, but at the same time, the switch must be very rugged and able to withstand shocks and jolts. For this reason, a metal envelope type switch is much more to be desired than the glass type, and the present invention is directed particularly to a cheap, simple, metal envelope mercury switch.

Other objects and advantages of the present invention will appear more fully from the following detailed description which, taken in conjunction with the accompanying drawing, will disclose to those skilled in the art, the particular construction and operation of the preferred form of the present invention.

In the drawing: Y

Figure l is a sectional view through one form of switch embodying the present invention;

Figure 2 is a modified view of the structure shown in Figure 1;

Figure 3 is a sectional View of another form of the invention;

Figure 4 is a sectional view showing a switch in which two similar metal cap members are employed; Y

Figure 5 is a further modification of the switch shown in Figure 4;

Figure 6 is an exploded view of a still further modification of the switch of Figures 1 and 2.

Figure 7 is a modification of the structure shown in Figure 3; and

Figure 8 is an assembled View of the switch shown in Figure 6.

Referring now in detail to the drawing, in Figure 1 I have provided a cup-shaped stamped metal cap 5 within which is seated an annular ceramic or similar refractory ring 6. Seated against the face of the ring 6 is the forward end I of a cylindrical sleeve portion 8 of a cup-shaped member 9 which, at its opposite end is provided with the enlarged thickened portion forming the radial shoulder le. Interposed between the annular fiange portion of the cap 5 and the sleeve portion 8 is an annular sleeve of fiber, rubber, or similar insulating material 5, which is adapted to have a pressed t within the open end of the cap 5. With such a construction, it will be apparent that the sleeve portion 8 of the member 9 is insulated from the cap member 5, both by the annular sleeve I 2 and by the ceramic ring 6. Disposed within the interior of the switch is a body of mercury I3 which is adapted when the switch is tilted in a counter-clockwise direction from .the position shown in Figure 1 to roll to the left hand end of the structure, thereby making a Y connection through the mercury between the cap 5 and the sleeve 8, thus closing the circuit through the switch structure.

It will be noted that in this form of the invention the external diameter of the cap 5 and the shoulder lil are equal, and consequently the entire switch structure can be disposed within a tubular holder and placed in position so that one end thereof may bear against a lamp base whereby, upon closing of the circuit through the switch, the lamp is actuated. Since the switch carries only a small current, the width of the ceramic ringl 6 may be reduced as there is little or no tendency for any arcingwithin the switch. It will be noted that the sleeve 8 and the ring 6 are of equal'internal diameter, thereby providing a smooth bore along which the mercury may roll, and introducing no barriers tending to restrict or hold back the mercury Vfrom one end of the switch to the other.

In Figure 2 a structure corresponding to that shown in Figure l is provided, except that in4 this form of the invention the ceramic ring 6 is omitted and in place thereof, the annular insulatingsleeve I2' is extended a suiiicient distance so as to form an axial spacer having an end flange I4 spacing the chamferred end 'I' of the sleeve portion 8' of the member 9 away from the base of the cap member 5. This provides for an insulating spacer therebetween, and as the cap member is pressed into position, it abuts against the flange III to be held away from the sleeve 8. This construction is also assembled by pressing the sleeve I2 over the sleeve 8', and then pressing the cap member 5 over the open end of the structure to a point such as shown in the drawing, providing the annular insulating ilange I4 between the end of the sleeve 8' and the base of the cap 5. the same manner as shown in connection with Figure 1, and constitutes merely a simplification thereof.

In Figure 3 a modified form of the inventionis shown in which a relatively heavy piece of bar stock is formed into a cup-shaped member indicated generally at I5. This member has one end thereof closed as indicated at I6', and is bored to provide the hollow passage I'I therein, The open end ci this member is provided.` with a tapered counterbore IS adapted to receive the ceramic insulating disc IS and the formed-rubber block 2G. The rubber block 2`II-is preferably of semi-hard rubber which may be pressed into the counterbored passageway I8 to=iorm a seal for the end oi the switch and is then held against withdrawal outwardly by striking over portions 22 at rthe peripheral edge of the opening I8. Extending through the `block 29 and the ceramic disc I9 `is theshank portion 23 of an electrode having a head portion 24 iorming'one terminal connection for the switch. A suitable body of mercury 25-within the -bore YI'I isadapted to be moved along the smooth floor of the switch into -andout of contact with the inner extending end 2$ of the electrode 23, thereby making and breaking the circuit between the cup-shaped member I5 and the electrode 2S. Here lagain it will be noted that the interior ci the switch is free of projections or barriers, and-provides a smooth floor for the mercury to roll on.

In Figure 4 I-have provided a switch structure which comprises a cylindrical insuiating sleevev member Sil having adjacent its center the thickened portion 32 Yforming oppositely facing shoulders 33and SII. These radial shoulders form stops against whichthe cup-shaped cap members v35 and 3 abut, these cap members being pressed over the external surfacel of the sleeve 33 into abutting engagement with the shoulders 33 and-2li. This press fit closesV the switch chamber 31 and formsV a substantially sealed chamber within which is disposedthe body o mercury 38.

Securedto the base of one o the cap members is an electrode pin 3:3 which is welded cr otherwise suitably secured'in axially extending position within the base of' the cap' member. The member 39 extends substantially to the center ofthe switch, and the` body ofmercury '58 when the switch is tilteol rolls downwardlyinto contact therewith to closeV the circuit between the cap Ymembers 35 and 3E'.

Since these members are `bothY of the same structure they can be vformed rapidly inA mass production by stamping and theV entiretswitch structure is very cheap and canbe easily assembled by automatic machinery.

The formof the Vinvention shownin-Figure 5 is similarlto thatl shown in Figure ayexceptthat one of thecap members has been axially length- 'Ihe switch is operated in.

cned and the rubber member comprises a solid block.

In this form of the invention the solid rubber block Il is provided with an axial bore therethrough carrying the electrode stem 42- which projects outwardly from one end of the block, as indicated at 43. The block is provided with the external annular shoulders 44 intermediate its ends, and a cap member 45 is pressed over the outer end of the block and has the electrode stud II?. welded or otherwise mechanically and electrically bonded thereto.

The opopsite cap member 46 is pressed over the opposite end of .the block 43 into abutting engagement with the radial shoulder G4, but is of appreciable length to form with the end of the block a switch chamber i1 within which is disposed the body of mercury 48. Upon tilting of the switch, the mercury 48 moves into and out of contact with the projecting end of the electrode, thereby` making and breaking the circuit through the switch.

It will be noted that in all forms of the'invention` the members are secured together to form the switch chamberV by' meansof press ts and the external diameter oftheswitch'is'uniform at both ends. Further, ituwillbe apparent that in each of the formsoi the invention, a smooth iioor or trackway for 4movement cf the mercury is provided and-the switches are symmetrical about their longitudinal axes so that no attention `need be'paid -to their'radial position within Vthe clampl or bracket.

In Figure 6 I have disclosed an improvement of the switch shown in Figures 1 and 2 in vwhich punch press operations-may be employed in as sembling the structure. The body member 9 of this'form has the cylindrical extension-8V over which is pressed the Bakelite sleeve I2, it-'being understood that the vbody of mercury .I 3-is already within the sleeve 8. An inner cap-5930i.. thin sheet material, and vpreferably vhaving the outwardly daring flange '52, is-then placed over the end of sleeve I2, after which the cap 53', of heavy turnedstock is pressed into `telescoping-relation over cap 5B. This swagesthe caprl'ange 'lwithin the cap 53, forming a tight pressed't, rendering the switch ail` tight and-locking the. caps against displacement, as clearly shown in Figure 8.

In Figure 7 the switch ofliigure 3`has been modifiedto provide a cup-shaped'shell-havi ing a, cylindrical counterbore 62Yreceivinglthe semi-hard rubber plug. 63 carryingthe electrode pin 64I. The shell has its end' spun'over to look the plug compressed `into sealing engagement with the bore. A suitable shoulderportion 65 insulates the electrode pin6 radially with/respect to the shell. If desired, Athe interior of this, or any of .theother switches shown may have a partial filling of triethanol'amine forl arc quenching and cooling.

It will be obvious that withconstructions of vthis type a very. rugged metal envelope type switch is provided which is simple-to-assemble and the parts of which can be economically made either by stamping or boringftofproducea-very economical structure. f

I am aware that various changes may Vb 'e-made in certain of the details of the invention hereinv disclosed and described, and Itherforedonot intend to be limited except as dened "by* the scope and spiritcf "the appended claims.

Iclaim: V

l. In a switch, a cylindrical insulating -sl'eeve;

a pair of cup-shaped electrode caps pressed over opposite ends of said sleeve and held in insulated relation thereby, a body of mercury in said sleeve and movable axially along the internal surface of said sleeve, said cap members having their internal facing surfaces exposed to said mercury at opposite ends of said sleeve, and an electrode pin on one of said cap members projecting axially through said sleeve to a point adjacent the other cap member and radially spaced from said internal sleeve surface a distance less than the meniscus height of said body of mercury, whereby said mercury contacts said pin at all times and is stabilized against undesired motion thereby.

2. The switch of claim l further characterized in the provision of an annular external rib intermediate the ends of said sleeve forming an abutment for the peripheral edges of said cap members.

3. In a switch, an insulating sleeve, a cupshaped cap member pressed over each end of said sleeve and supported thereon in insulated relation, the internal surface of said sleeve and the end faces of said cap members defining a cylindrical switch chamber, a body of mercury in said chamber movable over the internal surface of said sleeve as a runway upon tilting of said switch, and an internal pin on the end face of one of said cap members projecting axially through said chamber to a point adjacent the other cap member end face, said pin being spaced radially from said internal sleeve surface a distance less than the meniscus height of said mercury.

CHARLES W. TRAUTMAN. 

